Messages in this thread Patch in this message | | | From | Oleksandr Natalenko <> | Subject | [PATCH NOTFORMERGE 4/5] mm/madvise: employ mmget_still_valid for write lock | Date | Sun, 16 Jun 2019 10:58:34 +0200 |
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Do the very same trick as we already do since 04f5866e41fb. KSM hints will require locking mmap_sem for write since they modify vm_flags, so for remote KSM hinting this additional check is needed.
Signed-off-by: Oleksandr Natalenko <oleksandr@redhat.com> --- mm/madvise.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/mm/madvise.c b/mm/madvise.c index 9755340da157..84f899b1b6da 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -1049,6 +1049,8 @@ static int madvise_common(struct task_struct *task, struct mm_struct *mm, if (write) { if (down_write_killable(&mm->mmap_sem)) return -EINTR; + if (current->mm != mm && !mmget_still_valid(mm)) + goto skip_mm; } else { down_read(&mm->mmap_sem); } @@ -1099,6 +1101,7 @@ static int madvise_common(struct task_struct *task, struct mm_struct *mm, } out: blk_finish_plug(&plug); +skip_mm: if (write) up_write(&mm->mmap_sem); else -- 2.22.0
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